Reading device and image forming apparatus

ABSTRACT

A reading device includes a carriage movable in a sub-scanning direction, an optical sensor mounted on the carriage, the optical sensor being configured to scan an object placed on a contact glass, a reference scale used as a reference when a dimension of the object is computed based on an image obtained as the optical sensor scans the object, a flat gauge to be scanned by the optical sensor to calculate a corrective value used to correct the image obtained by the optical sensor, and circuitry to calculate the corrective value based on a scanned image including the reference scale and the flat gauge obtained by the optical sensor, and correct, based on the corrective value, a measurement image including an image of the object and an image of the reference scale obtained by the optical sensor and compute the dimension of the object based on the corrected measurement image.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is based on and claims priority pursuant to 35U.S.C. § 119(a) to Japanese Patent Application No. 2021-181209, filed onNov. 5, 2021, in the Japan Patent Office, the entire disclosure of whichis hereby incorporated by reference herein.

BACKGROUND Technical Field

Embodiments of the present disclosure relate to a reading device and animage forming apparatus.

Background Art

In the related art, reading devices that optically scan, for example,the shape of an object are known. Typically, the reading devices knownin the related art have a function to scan the object to be scannedplaced on a contact glass with an optical sensor mounted on a carriagethat moves along the contact glass. As a result, the shape of the objectto be scanned is obtained, the image data of the object is generated.

In such reading devices known in the art, for example, a reference scalethat is made of a hard component and has ticks at predeterminedintervals is placed on the reading face, and an image that includes theobject and the reference scale is scanned. Moreover, the position of theobject on the scanned image with reference to the ticks of the scale ismeasured in such reading devices known in the art. Due to such aconfiguration, the dimensions of the object on the image can bemeasured.

SUMMARY

Embodiments of the present disclosure described herein provide a readingdevice including a carriage movable in a sub-scanning direction, anoptical sensor mounted on the carriage, the optical sensor beingconfigured to scan an object placed on a contact glass, a referencescale used as a reference when a dimension of the object is computedbased on an image obtained as the optical sensor scans the object, aflat gauge to be scanned by the optical sensor to calculate a correctivevalue used to correct the image obtained by the optical sensor, andcircuitry configured to calculate the corrective value based on ascanned image including the reference scale and the flat gauge obtainedby the optical sensor, and correct, based on the corrective value, ameasurement image including an image of the object and an image of thereference scale obtained by the optical sensor and compute the dimensionof the object based on the corrected measurement image. In the readingdevice, the reference scale extends in a main scanning directionorthogonal to the sub-scanning direction outside a range of imageacquisition in which the optical sensor scans the object to obtain theimage of the object as the carriage moves and inside a maximum movementrange in which the carriage is movable and the optical sensor obtainsthe image of the object, and the flat gauge is arranged on the contactglass inside the range of image acquisition, where a plurality of firstreference lines drawn on a face of the contact glass are oriented in themain scanning direction.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of embodiments and the many attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings.

FIG. 1 is a schematic diagram illustrating a configuration of amultifunction peripheral (MFP) that serves as an image forming apparatusaccording to an embodiment of the present disclosure.

FIG. 2 is a diagram illustrating a hardware configuration of acontroller provided for an MFP according to an embodiment of the presentdisclosure.

FIG. 3 is a schematic block diagram illustrating a functionalconfiguration of an MFP according to an embodiment of the presentdisclosure.

FIG. 4 is a diagram illustrating an outline of an optical system mountedon a carriage, according to an embodiment of the present disclosure.

FIG. 5A, FIG. 5B, and FIG. 5C are diagrams each illustrating a causethat skews a carriage, according to an embodiment of the presentdisclosure.

FIG. 6 is a plan view of a scanner unit according to an embodiment ofthe present disclosure.

FIG. 7 is a diagram illustrating an arrangement of a reference scaleprovided for a scanner unit according to an embodiment of the presentdisclosure.

FIG. 8 is a diagram illustrating a scanning range when an object to bescanned is a three-dimensional object, according to an embodiment of thepresent disclosure.

FIG. 9A, FIG. 9B, and FIG. 9C are diagrams illustrating the measuringprocesses for a part or component, a scanned image, and a registeredimage, respectively, according to an embodiment of the presentdisclosure.

FIG. 10 is a flowchart of corrective-value calculation processesaccording to an embodiment of the present disclosure.

FIG. 11A and FIG. 11B are diagrams each illustrating the operation of ascanner unit according to an embodiment of the present disclosure.

FIG. 12 is a flowchart of the measuring processes for a part orcomponent, according to an embodiment of the present disclosure.

FIG. 13 is a flowchart of the processes of measuring the dimensions ofan object, according to an embodiment of the present disclosure.

FIG. 14A, FIG. 14B, and FIG. 14C are diagrams each illustrating acorrected image including various kinds of objects to be scanned and areference scale, according to an embodiment of the present disclosure.

FIG. 15 is a flowchart of the measuring processes for a part orcomponent, according to an alternative embodiment of the presentdisclosure.

The accompanying drawings are intended to depict embodiments of thepresent disclosure and should not be interpreted to limit the scopethereof. The accompanying drawings are not to be considered as drawn toscale unless explicitly noted.

DETAILED DESCRIPTION

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the presentdisclosure. As used herein, the singular forms “a”, “an”, and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“includes” and/or “including”, when used in this specification, specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

In describing example embodiments illustrated in the drawings, specificterminology is employed for the sake of clarity. However, the presentdisclosure is not intended to be limited to the specific terminology soselected and it is to be understood that each specific element includesall technical equivalents that have the same structure, operate in asimilar manner, and achieve a similar result.

An image forming apparatus and a reading device according to anembodiment of the present disclosure are described below with referenceto the drawings.

FIG. 1 is a schematic diagram illustrating a configuration of amultifunction peripheral (MFP) 1 that serves as an image formingapparatus according to an embodiment of the present disclosure.

The MFP 1 is provided with a scanner unit 100 that serves as a readingdevice according to embodiments of the present disclosure and an imageforming unit 200 that forms an image on a sheet-like recording medium.The device according to embodiments of the present disclosure may beapplied to a single unit of reading device such as the scanner unit 100instead of the MFP 1.

The scanner unit 100 according to the present embodiment includes acontact glass 101, an optical sensor 102, and a carriage 103. Thecontact glass 101 according to the present embodiment serves as amounting table on which an object to be scanned B is to be mounted. Theoptical sensor 102 is an image sensor that irradiates the object to bescanned B placed on the contact glass 101 with light and obtains anoptical image of the object to be scanned B based on the reflectedlight. The carriage 103 moves in the sub-scanning direction with respectto the object to be scanned B such that the optical sensor 102 can scanthe object to be scanned B.

The optical sensor 102 is arranged in a line in the main scanningdirection orthogonal to the sub-scanning direction in which the carriage103 moves. The scanner unit 100 according to the present embodiment isconfigured to obtain an image of the entirety of the object to bescanned B as the object to be scanned B is scanned while moving the linein the sub-scanning direction in which the optical sensor 102 scans theobject.

The scanner unit 100 according to the present embodiment is alsoprovided with an automatic document feeder (ADF) 500 that serves as amedium conveyance unit that conveys a sheet-like object to be scanned Bto the contact glass 101.

The image forming unit 200 according to the present embodiment isprovided with a medium accommodating unit 201 that stores a sheet P thatserves as a sheet-like medium, and an image forming device 202 thatforms an image on the sheet P. The image forming device 202 according tothe present embodiment can form an image read by the scanner unit 100 onthe sheet P.

FIG. 2 is a diagram illustrating a hardware configuration of thecontroller 150 provided for the MFP 1 according to the presentembodiment.

As illustrated in FIG. 2 , the MFP 1 according to the present embodimenthas a configuration similar to that of known information processingdevices such as personal computers (PCs) and servers. In other words, acentral processing unit (CPU) 10, a random access memory (RAM) 20, aread only memory (ROM) 30, a hard disk drive (HDD) 40, and an interface(IX) 50 are connected to each other through a bus 90 in the MFP 1according to the present embodiment. The interface 50 is coupled to adisplay unit 60, an operation panel 70, and dedicated devices 80. Thededicated device 80 includes the scanner unit 100 and the image formingunit 200.

The CPU 10 is a computation unit that controls all operations of the MFP1. The RAM 20 is a volatile memory where data can be read and written athigh speed, and is used as a work area when the CPU 10 processes data.The ROM 30 is a read-only nonvolatile memory in which firmware programsor the like are stored. The HDD 40 is a data readable/writablenonvolatile memory in which, for example, an operating system (OS),various kinds of control programs such as an applied-voltage controlprogram, and an application program are stored.

The interface (I/F) 50 connects, for example, various kinds of hardwareand networks to the bus 90, and controls these elements. The displayunit 60 according to the present embodiment is a user interface thatallows a user to visually check the status of the MFP 1, and isimplemented by a display device such as a liquid crystal display (LCD).The operation panel 70 is a user interface through which the data isinput to the MFP 1.

In such a hardware configuration, the programs that are stored in theROM 30 and the HDD 40, or in another recording medium such as an opticaldisk are read by the RAM 20, and the CPU 10 performs computation basedon these programs loaded into the RAM 20. This series of processesconfigures a software controller. The software controller as configuredabove and hardware are combined to configure a functional block thatimplements the functions of the MFP 1 according to the presentembodiment.

FIG. 3 is a schematic block diagram illustrating a functionalconfiguration of the multifunction peripheral (MFP) 1 according to thepresent embodiment.

In FIG. 3 , electrical connections are indicated by solid-line arrows,and the flow of transfer sheets or a bundle of documents is indicated byarrows with broken lines.

As illustrated in FIG. 3 , the MFP 1 according to the present embodimentincludes a controller 150, a sheet feeding table 203, a print engine300, a printed-sheet output tray 400, an automatic document feeder (ADF)500, a scanner engine 600, a scanned-sheet output tray 700, a displaypanel 800, and a network interface (I/F) 900. The controller 150according to the present embodiment includes a main controller 151, anengine controller 152, an image processing unit 153, an operationdisplay controller 154, and an input and output controller 155.

The sheet feeding table 203 according to the present embodiment feeds atransfer sheet to the print engine 300 that serves as an image formingdevice. The print engine 300 serves as an image forming device thatdraws an image by forming and outputting an image on the transfer sheetconveyed from the sheet feeding table 203. The print engine 300according to the present embodiment may be an image formation mechanismusing an electrophotographic method. The transfer sheet on which animage has been formed by the print engine 300 is ejected to theprinted-sheet output tray 400. The print engine 300 according to thepresent embodiment is implemented by the dedicated device 80 asillustrated in FIG. 2 .

The ADF 500 automatically conveys the object to be scanned B to aposition where the object to be scanned B can be scanned by the scannerengine 600 that executes some of the processes in the scanner unit 100.The scanner engine 600 according to the present embodiment is a documentreading device including a photoelectric conversion element thatconverts the optical information into an electrical signal, andgenerates image data by optically scanning and reading the documentautomatically conveyed by the ADF 500 or the document placed on adocument-stage glass. The document that is automatically conveyed by theADF 500 and scanned by the scanner engine 600 is ejected to thescanned-sheet output tray 700. The ADF 500 and the scanner engine 600according to the present embodiment are implemented by the dedicateddevices 80 as illustrated in FIG. 2 .

The display panel 800 is an output interface on which the status of theMFP 1 is visually displayed, and also is an input interface such as atouch panel through which the MFP 1 is directly operated and the data isinput to the MFP 1. Moreover, the display panel 800 has a function todisplay an image through which the operation made by a user is receivedand accepted. The display panel 800 is implemented by the display unit60 and the operation panel 70 as illustrated in FIG. 2 .

The network interface 900 according to the present embodiment is aninterface through which the MFP 1 communicates with other devices suchas administrator terminals and personal computers (PCs) through thenetwork, and interfaces such as Ethernet (registered trademark),universal serial bus (USB) interfaces, Bluetooth (registered trademark),wireless fidelity (Wi-Fi) (registered trademark), and FeliCa (registeredtrademark) are used. As described above, the MFP 1 according to thepresent embodiment receives the image data to be printed and variouskinds of control commands such as a printing request from the terminalsconnected through the network interface 900. The network interface 900is implemented by the interface 50 as illustrated in FIG. 2 .

The controller 150 is configured by a combination of software andhardware. More specifically, the controller 150 is configured by thecombination of hardware such as an integrated circuit and a softwarecontroller that is implemented as control programs such as the firmwarestored in a nonvolatile memory such as the ROM 30 or the HDD 40 areloaded into the RAM 20 and the CPU 10 performs computation based onthese loaded programs. The controller 150 serves as a controller thatcontrols the entirety of the MFP 1. Accordingly, in the presentembodiment, the controller 150 serves as an applied-voltage controldevice.

The main controller 151 plays a role in controlling the multipleelements of the controller 150, and gives a command to each one of themultiple elements of the controller 150. Moreover, the main controller151 controls the input and output controller 155, and accesses otherdevices through the network interface 900 and the network. The enginecontroller 152 controls or drives a driver such as the print engine 300and the scanner engine 600.

The image processing unit 153 according to the present embodiment iscontrolled by the main controller 151, and generates drawing informationas output data based on the image data written in, for example, thepage-description language (PDL). Such image data may be, for example,the documental data or image data included in the input print job. Thedrawing information is information such as cyan, magenta, yellow, andblack (CMYK) bitmap data, and is used to draw an image to be formed whenthe print engine 300 that serves as an image forming device performsimage-forming operation.

Further, the image processing unit 153 processes the data of imaginginput from the scanner engine 600 to generate the image data. Thegenerated image data is stored in the MFP 1 as the data obtained as aresult of the scanning processes, or is sent to other devices throughthe network interface 900 or the network. Note that the MFP 1 accordingto the present embodiment can directly receive the drawing informationinstead of the image data and can form and output an image based on thedirectly-input drawing information.

The operation display controller 154 displays information on the displaypanel 800, or notifies the main controller 151 of the data input throughthe display panel 800. The input and output controller 155 inputs thesignals and commands input through the network interface 900 and thenetwork to the main controller 151.

A detailed configuration of the scanner unit 100 is described below.

FIG. 4 is a diagram illustrating an outline of an optical system mountedon the carriage 103, according to the present embodiment.

As illustrated in FIG. 4 , the light that is emitted from the lightsource provided for the carriage 103 is reflected by the object to bescanned B, and the reflected light enters the reduction optical systemalong an optical path h. Then, the reflected light is reflected by afirst mirror 1031.

The light reflected by the first mirror 1031 is reflected by the secondmirror 1032, the third mirror 1033, the fourth mirror 1034, the fifthmirror 1035, and the sixth mirror 1036, passes through the lens 1037,and enters the optical sensor 102. The optical sensor 102 according tothe present embodiment is, for example, a charge coupled device (CCD)sensor.

The image of the object to be scanned B is converted into an electricalsignal based on the light detected by the optical sensor 102, and thecontroller 150 performs predetermined processing on the obtainedelectrical signal. As a result, the image data of the object to bescanned B is generated.

FIG. 5A, FIG. 5B, and FIG. 5C are diagrams each illustrating a causethat skews the carriage 103, according to the present embodiment.

As illustrated in FIG. 5A, FIG. 5B, and FIG. 5C, the scanner unit 100further includes a driving mechanism 104 that moves the carriage 103 inthe sub-scanning direction. The carriage 103 is extended in the mainscanning direction, and is moved by the driving mechanism 104 in thesub-scanning direction.

As illustrated in FIG. 5A, the driving mechanism 104 includes a motor1041, a driving pulley 1042, a driven pulley 1043, a timing belt 1044,and a guide rod 1045. The driving pulley 1042 and the driven pulley 1043are disposed separately from each other in the sub-scanning direction.The timing belt 1044 is looped around the driving pulley 1042 and thedriven pulley 1043, and is connected to the carriage 103. The guide rod1045 extends in the sub-scanning direction and guides the movement ofthe carriage 103.

As the driving force of the motor 1041 is conveyed and the drivingpulley 1042 rotates, the timing belt 1044 circulates between the drivingpulley 1042 and the driven pulley 1043. As a result, the carriage 103reciprocates in the sub-scanning direction as guided by the guide rod1045.

As illustrated in FIG. 5B, in order for the carriage 103 to move alongthe guide rod 1045, a gap or play is required between the carriage 103and the guide rod 1045. The timing belt 1044 and the guide rod 1045 aredisposed separately from each other in the main scanning direction. Thegap, backlash, or play between the carriage 103 and the guide rod 1045may be present at the fitting part in the main scanning directionbetween the carriage 103 and the outer circumferential surface of theguide rod 1045. As a result, as illustrated in FIG. 5C, the carriage 103that is moved by the driving force conveyed from the timing belt 1044may move in an inclined manner with respect to the position of the guiderod 1045 that serves as a starting point.

In other words, the position where a force is applied to the carriage103 in order to move the carriage 103 in the sub-scanning direction isnear one of the pair of edges of the carriage 103 in the main scanningdirection. Once the timing belt 1044 fixed onto the above positionstarts circulating, the ends of the carriage 103 tend to rotate in thecirculating direction of the timing belt 1044 around the fitting partbetween the carriage 103 and the guide rod 1045. Due to such anoperation, when the carriage 103 is inclined with reference to theposture when the carriage 103 is orthogonal to the guide rod 1045 whilemoving in the sub-scanning direction. As a result, when the scanning isperformed on the object to be scanned B, scanning is performed while thecarriage 103 is moving in the sub-scanning direction with the posturebeing inclined with respect to the desired posture in the main scanningdirection.

FIG. 6 is a plan view of the scanner unit 100 according to the presentembodiment in which the contact glass 101 is viewed from the mountingtable on which the object to be scanned B is placed.

The rear side of the contact glass 101 as illustrated in FIG. 6 servesas the reading face of the contact glass 101. The rear side of thecontact glass 101 corresponds to the A-side of the sheet in the depthdirection.

As illustrated in FIG. 6 , on the mounting table of the contact glass101, a document-size reference line 1011 is indicated that serves as areference position when the flat sheet-like object to be scanned B isplaced.

In FIG. 6 , the scanner unit 100 is in standby mode before the scanningoperation is to be started. Accordingly, the carriage 103 is waiting atthe carriage home position 1012. The carriage home position 1012corresponds to a standby position before the carriage 103 starts thescanning operation.

The scanner unit 100 according to the present embodiment has aplanar-medium's maximum scanning area 1013 that indicates the maximumrange of image acquisition in which the object to be scanned B isscanned to obtain an image and a carriage's maximum scanning area 1014that indicates the maximum range of movement in which the carriage 103moves and the optical sensor 102 can perform scanning, and these areasof the scanner unit 100 are set in advance. In other words, thecarriage's maximum scanning area 1014 is equivalent to the area that issurrounded by a pair of edges of the maximum range in which the carriage103 moves for scanning at furthest and a pair of edges of the carriagehome position 1012 on the other side.

In FIG. 6 , the planar-medium's maximum scanning area 1013 when theobject to be scanned B is a sheet P of A3 size is indicated by a shadedarea.

FIG. 7 is a diagram illustrating an arrangement of the reference scale105 provided for the scanner unit 100 according to the presentembodiment.

As illustrated in FIG. 7 , the reference scale 105 includes a mainscanning direction scale 1051 and a sub-scanning direction scale 1052.As illustrated in FIG. 7 , the main scanning direction scale 1051extends in the main scanning direction outside the edge of themaximum-size document readable on the contact glass 101 in thesub-scanning direction. The sub-scanning direction scale 1052 extends inthe sub-scanning direction outside the edge of the maximum-size documentreadable on the contact glass 101 in the main scanning direction.

Both the main scanning direction scale 1051 and the sub-scanningdirection scale 1052 are arranged at positions corresponding to theoutside of the planar-medium's maximum scanning area 1013 and the insideof the carriage's maximum scanning area 1014. As illustrated in FIG. 7 ,the reference scale 105 has ticks on the reading face on the contactglass 101, and such ticks of the scale serve as a reference when thedimensions of an object are measured. On the main scanning directionscale 1051, the ticks of the scale that extend in the sub-scanningdirection are drawn at positions separated from each other in the mainscanning direction. On the sub-scanning direction scale 1052, the ticksof the scale that extend in the main scanning direction are drawn atpositions separated from each other in the sub-scanning direction.

The reference scale 105 according to the present embodiment may bedisposed below the contact glass 101 around the carriage 103, or may bedisposed above the contact glass 101 where the object to be scanned B isplaced.

The degree of precision in the correction of the scanning by the opticalsensor 102 is enhanced when the reference scale 105 is arranged on themounting table of the object to be scanned B on the top face. As thereference scale 105 is used for correction of the optical sensor 102,ticks are to be arranged on the downside so as to face the carriage 103.In other words, the reference scale 105 may be arranged on both sides ofthe contact glass 101. If the reference scale 105 are arranged on bothsides of the contact glass 101, the position of the reference scale 105becomes visually recognizable, and the optical sensor 102 that faces thelower surface of the contact glass 101 in an upward direction can obtainthe images of the reference scale 105 and the object to be scanned B atthe same time.

Regarding the face of the reference scale 105 that is arranged to facethe carriage 103, it is desired that the color indicating the ticks ofthe scale be different from the color of the base part on which theticks of the scale are formed so as not to reflect the light emittedfrom the light source provided for the carriage 103. For example, thecolor of the lines indicating the ticks of the scale is made whiteusing, for example, steel use stainless (SUS) polishing, and the degreeof contrast of the lines on the image can be increased for increasedvisual recognizability.

Alternatively, steel use stainless (SUS) may be used as the material forthe reference scale 105, and the ticks of the scale may be formed inblack. Such a configuration does not affect the processes ofsimultaneously obtaining an image and the object to be scanned B.

FIG. 8 is a diagram illustrating a scanning range when the object to bescanned B is a three-dimensional object, according to the presentembodiment.

As illustrated in FIG. 8 , a part measurement range 1015 is arranged ata position different from the planar-medium's maximum scanning area 1013that is the scanning range when the object to be scanned B is planar. Aportion of the part measurement range 1015 in the sub-scanning directionaround the turning point in the movement of the carriage 103 serves as areference position for placement. As the range in the main scanningdirection is set so as to be distributed with respect to the center ofthe optical path, the center point in the main scanning direction servesas a reference position for placement.

Regarding the moving direction of the carriage 103 in the sub-scanningdirection and the optical direction in which the optical sensor 102mounted on the carriage 103 optically scans the object to be scanned Bin the main scanning direction, the positional displacement of themoving direction of the carriage 103 tends to be greater than theoptical direction. In order to handle such a situation, the intervals atwhich the ticks of the sub-scanning direction scale 1052 are madenarrower than the intervals at which the ticks of the main scanningdirection scale 1051 to further enhance the precision of themeasurement. In other words, in the reference scale 105, thesub-scanning direction scale 1052 is a finer scale than the mainscanning direction scale 1051.

The corrective-value calculation processes to be performed by thescanner unit 100 are described below with reference to FIG. 9A, FIG. 9B,FIG. 9C, and FIG. 10 .

FIG. 9A, FIG. 9B, and FIG. 9C are diagrams illustrating the measuringprocesses for a part or component, a scanned image, and a registeredimage, respectively, according to the present embodiment.

FIG. 10 is a flowchart of corrective-value calculation processes thatcan be performed in the scanner unit 100, according to the presentembodiment.

Firstly, in a step S1001, a pressure plate is opened to place the objectto be scanned B on the mounting table of the contact glass 101. Thepressure plate according to the present embodiment in the configurationor structure that includes the ADF 500 is a plate-like component thatcovers the contact glass 101 to hold a flat object placed on the contactglass 101.

Subsequently, in a step S1002, a flat gauge 106 is placed on themounting table of the contact glass 101. As illustrated in FIG. 9A, theflat gauge 106 according to the present embodiment is a sheet-likemember such as a sheet of paper or a flat plate on which a plurality offirst reference lines 1061 and a plurality of second reference lines1062 are drawn.

The multiple first reference lines 1061 and the multiple secondreference lines 1062 are arranged at positions separate from each other.Further, the multiple first reference lines 1061 and the multiple secondreference lines 1062 extend in directions perpendicular to each other.In other words, the multiple first reference lines 1061 and the multiplesecond reference lines 1062 are arranged in a grid pattern on the flatgauge 106. The flat gauge 106 according to the present embodiment isarranged in the planar-medium's maximum scanning area 1013 where themultiple first reference lines 1061 are oriented in the main scanningdirection and the multiple second reference lines 1062 are oriented inthe sub-scanning direction.

Subsequently, in a step S1003, a corrective-value calculation key thatis arranged on the operation panel 70 is touched or pressed down tostart the scanning process. Once the scanning process starts, firstly,in a step S1004, the carriage 103 starts operating, and scans the objectto be scanned B using the optical sensor 102 as the carriage 103 moves.

In a step S1005, corrective-value calculator scans the flat gauge 106and the reference scale 105 while the carriage 103 is being moved to thecarriage's maximum scanning area 1014, and obtains and stores thescanned image including the flat gauge 106 and the reference scale 105in a storage area. In so doing, if the carriage 103 is skewed asillustrated in FIG. 5C while being moved, the scanned image that isobtained in the step S1005 is distorted as illustrated in FIG. 9B.

On the other hand, as illustrated in FIG. 9C, the registered image isstored in the HDD 40 that serves as a memory.

The registered image includes the reference scale 105 and the flat gauge106 in which the multiple first reference lines 1061 are oriented in themain scanning direction and the multiple second reference lines 1062 areoriented in the sub-scanning direction. In other words, the registeredimage is an image of the state as illustrated in FIG. 9A, and thedistortion or deformation therein is corrected in the registered image.The registered image is generated in advance and stored in the HDD 40.

Subsequently, in a step S1006, the corrective-value calculator comparesthe scanned image illustrated in FIG. 9B with the registered imageillustrated in FIG. 9C to calculate a corrective value. The correctivevalue according to the present embodiment is a numerical value thatindicates the amount of movement for each pixel of the scanned image tomove such that the scanned image obtained by the optical sensor 102 willmove to get close to or match the registered image stored in the HDD 40.

More specifically, the corrective-value calculator specifies acorresponding pixel in the registered image, which indicates the sameportion of the image, for each of a plurality of pixels that make up thescanned image. Subsequently, the corrective-value calculator calculatesas a corrective value the amount of misalignment or the amount ofmovement of the pairs of pixels that correspond to each other betweenthe scanned image and the registered image.

For example, in FIG. 9B and FIG. 9C, the pixel P1 and the pixel P2 aremoved by the length indicated by each arrow based on the correctivevalues for the pixel P1 and the pixel P2, respectively, in the directionindicated by each arrow. On the other hand, the corrective value for thepixel P3 is zero as the pixel in FIG. 9B matches the pixel in FIG. 9C.In other words, the corrective value may differ for each one of thepixels. Then, in a step S1007, the corrective-value calculator storesthe calculated corrective value in the HDD 40.

The corrective-value calculator may calculate a corrective value foreach one of all the pixels that make up the scanned image, or maycalculate a corrective value for each set of a plurality of adjacentpixels. Such a corrective value for each set of a plurality of adjacentpixels may be referred to as a pixel block in the following description.Alternatively, the corrective-value calculator may calculate acorrective value for each row of pixels that are adjacent to each otherin the sub-scanning direction. As a method of processing an image usinga corrective-value calculator is known in the art, its detaileddescription is omitted.

The processes that are described with reference to FIG. 9A, FIG. 9B,FIG. 9C, and FIG. 10 , which are performed by the corrective-valuecalculator, are implemented by the computation executable in the maincontroller 151 and the image processing unit 153. In the above-describedprocess, the image processing unit 153 performs a process of specifyingeach image portion on the scanned image including the reference scale105 and the flat gauge 106. The results of the above processes arepassed to the main controller 151, and the main controller 151 executesthe processes of computing the corrective value.

The measuring processes for a part or component to be performed by thescanner unit 100 are described below with reference to FIG. 11A and FIG.11B.

FIG. 11A and FIG. 11B are diagrams each illustrating the operation ofthe scanner unit 100 according to the present embodiment.

FIG. 11A illustrates an image obtained by performing the scanningprocesses on the object to be scanned B when the object to be scanned Bis a flat object and is a sheet P of A3 size.

In this case, an image is obtained in a range of 420 mm×297 mm.

In the present embodiment described with reference to FIG. 11B, theobject to be scanned B is a three-dimensional object and scanning isperformed to a movable range of the carriage 103 to obtain an image ofthe object.

In this case, for example, an image of the object to be scanned B and animage of the reference scale 105 are simultaneously obtained from arange of 440 mm×305 mm.

Then, the image portion of the reference scale 105 is compared with theimage portion of the object to be scanned B included in the obtainedimage, and the dimensions of the object to be scanned B are measured.

FIG. 12 is a flowchart of the measuring processes for a part orcomponent that can be performed by the scanner unit 100, according tothe present embodiment.

The flowchart in FIG. 12 illustrates a case in which the object to bescanned B is a three-dimensional object.

Firstly, in a step S1201, the pressure plate is opened to place theobject to be scanned B on the mounting table of the contact glass 101.Subsequently, in a step S1202; the object to be scanned B is placed onthe mounting table of the contact glass 101.

Subsequently, in a step S1203, a part measurement key that is arrangedon the operation panel 70 is touched or pressed down to start thescanning process. Once the scanning process starts, firstly, in a stepS1204, the carriage 103 starts operating, and the optical sensor 102starts scanning the object to be scanned B as the carriage 103 moves.

In a step S1205, the object to be scanned B is scanned by a dimensioncomputation unit while the carriage 103 is being moved to the carriage'smaximum scanning area 1014. As a result, the dimension computation unitobtains a measured image including the object to be scanned B and thereference scale 105, and stores the measured image in a storage area.

FIG. 13 is a flowchart of the processes of measuring the dimensions ofan object, according to the present embodiment.

Subsequently, in a step S1206 as illustrated in FIG. 13 , the dimensioncomputation unit performs the processes of measuring the dimensions ofan object. In the processes of measuring the dimensions of an object,the measured image is corrected, and the portion of the reference scale105 and the portion of the object to be scanned B that are included inthe corrected measured image are specified. By comparing these specifiedimages with each other, the dimensions of the object to be scanned B canbe measured. FIG. 13 is a flowchart of the processes executed in thestep S1206 where the dimensions of an object are measured, according tothe present embodiment.

Firstly, in a step S1301, the dimension computation unit corrects themeasured image obtained in the step S1205 with the corrective valuecalculated in the step S1006. More specifically, the dimensioncomputation unit moves the multiple pixels of the measurement imagebased on a corresponding corrective value. As a result, a correctedimage in which the distortion of the measured image has been correctedis generated.

Subsequently, in a step S1302, the dimension computation unit extractsthe ticks of the reference scale 105 and the edges of the object to bescanned B from the corrected image. As a method of extracting a specificportion from the corrected image, such as edge detection, is known inthe art, its detailed description is omitted.

Subsequently, in a step S1303, the dimension computation unit determinesthe dimensions of the extracted object to be scanned B based on thespacing among the extracted ticks of the reference scale 105. Morespecifically, the dimension computation unit multiplies thepredetermined interval of the ticks of the scale in micrometer (μm) bythe number of ticks of the scale facing the contours of the object to bescanned B whose dimensions are to be specified. As a result, thedimensions of the object can be determined. When at least one of theedges of the object to be scanned B is positioned between the adjacentpairs of ticks of the scale, the dimension computation unit prorates thenumber of pixels between such adjacent pairs of ticks of the scale. Asthe concrete processes of determining the dimensions of an object areknown in the related art, its detailed description is omitted.

Finally, in a step S1207 as illustrated in FIG. 12 , a dimensionmeasuring device displays the result of the measuring process on thedisplay unit 60, and terminates the scanning processes of athree-dimensional object.

A method of determining the various kinds of dimensions of objects to bescanned B1, B2, and B3 in the step S1303 is described below withreference to FIG. 14A, FIG. 14B, and FIG. 14C.

FIG. 14A, FIG. 14B, and FIG. 14C are diagrams each illustrating acorrected image including various kinds of objects to be scanned B1 B2,and B3 and the reference scale 105, according to the present embodiment.

As illustrated in FIG. 14A, when the dimension D1 of the object to bescanned B1 having a rectangular shape is to be determined, the dimensioncomputation unit counts the number of the ticks of the main scanningdirection scale 1051 between a vertex a1 and a vertex a2 of the objectto be scanned B1. When the dimension D2 of the object to be scanned B1is to be determined, the dimension computation unit counts the number ofthe ticks of the sub-scanning direction scale 1052 between the vertex a2and a vertex a3 of the object to be scanned B1.

As illustrated in FIG. 14B, when the dimension D3 of the object to bescanned B2 having a rectangular shape is to be determined, the dimensioncomputation unit determines a dimension D4 between a vertex a4 and avertex a5 of the object to be scanned B1 in the main scanning directionand a dimension D5 between the vertex a4 and the vertex a5 of the objectto be scanned B1 in the sub-scanning direction. A method of determiningthe dimension D4 and the dimension D5 is similar to the method describedwith reference to FIG. 14A.

Then, the dimension computation unit determines the dimension D3 basedon the dimension D4 and the dimension D5 using the Pythagorean theorem.

As illustrated in FIG. 14C, when the diameter D6 of the object to bescanned B3 having a circular shape is to be determined, the dimensioncomputation unit adopts a method similar to the method described asabove with reference to FIG. 14A to determine the maximum dimension ofthe object to be scanned B3 in the main scanning direction and themaximum dimension of the object to be scanned B3 in the sub-scanningdirection. Then, the dimension computation unit obtains the average ofthe maximum size in the main scanning direction and the maximum size inthe sub-scanning direction, and determines the obtained average to bethe diameter D6.

FIG. 15 is a flowchart of the measuring processes for a part orcomponent that can be performed by the scanner unit 100, according to analternative embodiment of the present disclosure.

The flowchart in FIG. 15 illustrates the processes to be performed whenthe object to be scanned B is a three-dimensional object and a desiredportion to be measured is specified.

In a similar manner to the first case of the present disclosure asdescribed above, firstly, in a step S1501, the pressure plate is openedto place the object to be scanned B on the mounting table of the contactglass 101, and then, in a step S1502, the object to be scanned B isplaced on the mounting table of the contact glass 101. Subsequently, ina step S1503, a preview key that is arranged on the operation panel 70is touched or pressed down to start a preview process.

In the preview process, only the image of the object to be scanned B isobtained, and the obtained image is displayed on the display unit 60 asa preview. In other words, firstly, in a steps S1504, the dimensionmeasuring device drives the carriage 103 to operate, and scans theobject to be scanned B using the optical sensor 102 as the carriage 103moves. In a step S1505, the scanner unit 100 according to the presentembodiment scans the object to be scanned B in the part measurementrange 1015 in which the object to be scanned B is to be scanned whilemoving the carriage 103, and obtains the image of the object to bescanned B at the same time. Then, the obtained image of the object to bescanned B is stored in the storage area.

Subsequently, in a step S1506, the dimension measuring device causes thedisplay unit 60 to display the image stored in the storage area as apreview image. Then, in a step S1507, the portion to be measured on theimage displayed on the display unit 60 is determined through theoperation panel 70. After the portion to be measured is specified, in astep S1508, the part measurement key that is arranged on the operationpanel 70 is touched or pressed down to start the scanning process.

Once the scanning process starts, the scanner unit 100 according to thepresent embodiment scans the object to be scanned B using the opticalsensor 102 as the carriage 103 moves, and such scanning of the object tobe scanned B is carried out while the carriage 103 is being moved to thecarriage's maximum scanning area 1014. As a result, the measured imagesincluding the image of the reference scale 105 and the image of theobject to be scanned B within range of the specified portion to bemeasured can be obtained, and in a step S1509, the dimension measuringdevice stores the obtained images in the storage area.

Subsequently, in a step S1510, the dimension measuring device performsprocesses of measuring the dimensions of an object as illustrated inFIG. 13 . Finally, in a step S1511, the dimension measuring devicedisplays the result of the measuring process on the display unit 60, andterminates the scanning processes of a three-dimensional object.

The processes that are described with reference to FIG. 12 , FIG. 13 ,and FIG. 15, which are performed by the dimension computation unit, areimplemented by the computation executable in the main controller 151 andthe image processing unit 153. In the above-described process, the imageprocessing unit 153 performs the processes of determining the imageportions of the object to be scanned B and the reference scale 105 onthe scanned image obtained by simultaneously obtaining the images of theobject to be scanned B and the reference scale 105. The results of theabove processes are passed to the main controller 151, and the maincontroller 151 executes the processes of computing the dimensions of theobject.

According to the present embodiment, the measurement image is correctedusing the corrective value calculated using the flat gauge 106.Accordingly, the accuracy of measurement of the dimensions of the objectto be scanned B using the reference scale 105 can be prevented fromdeteriorating.

According to the above-described embodiment, the multiple firstreference lines 1061 and the multiple second reference lines 1062orthogonal to each other are added to the flat gauge 106. As a result,the corrective value in the main scanning direction and the correctivevalue in the sub-scanning direction can be calculated at the same time.As a result, the measurement image can be corrected with a high degreeof precision. However, when the carriage 103 is skewed as illustrated inFIG. 5A, FIG. 5B, and FIG. 5C, it is sufficient as long as the multiplefirst reference lines 1061 are drawn on the flat gauge 106 and thecorrective value in the sub-scanning direction is obtained.

In the processes of measuring the dimensions of an object described asabove with reference to FIG. 13 , after the entirety of the measuredimage is corrected, the ticks of the reference scale 105 and the edgesof the object to be scanned B are extracted from the corrected image.However, the procedure according to the above embodiments of the presentdisclosure is not limited thereby. Alternatively, the dimensioncomputation unit may correct only the extracted portion using thecorrective value after the reference scale 105 and the object to bescanned B are extracted from the measured image. As a result, it issufficient as long as a desired portion in the measured image isselectively corrected, and the processing speed can be increased.

In the above embodiments of the present disclosure, the corrective-valuecalculation processes that are described as above with reference to FIG.10 are performed when the corrective-value calculation key that isarranged on the operation panel 70 is touched or pressed down. Due tosuch a configuration, when the environment in which the MFP 1 isinstalled is changed, instructions to perform the corrective-valuecalculation processes can be given in an explicit manner. Note also thatthe timing at which the corrective-value calculation processes areperformed is not limited to the timing according to the above-describedembodiments of the present disclosure.

Alternatively, the controller 150 may perform the corrective-valuecalculation processes described as above with reference to FIG. 10 inresponse to the length of time elapsed since the scanner unit 100 of theMFP 1 started operating exceeding a predetermined operating time, andmay then update the corrective value that is stored in the HDD 40. As aresult, a corrective value can appropriately be calculated in accordancewith the wear and tear or the deterioration over time of a drivingcomponent or a sliding component.

Note that numerous additional modifications and variations are possiblein light of the above teachings. It is therefore to be understood thatwithin the scope of the appended claims, the embodiments of the presentdisclosure may be practiced otherwise than as specifically describedherein. For example, elements and/or features of different illustrativeembodiments may be combined with each other and/or substituted for eachother within the scope of this disclosure and appended claims.

Note that numerous additional modifications and variations are possiblein light of the above teachings. It is therefore to be understood thatwithin the scope of the appended claims, the embodiments of the presentdisclosure may be practiced otherwise than as specifically describedherein. For example, elements and/or features of different illustrativeembodiments may be combined with each other and/or substituted for eachother within the scope of this disclosure and appended claims.

Any one of the above-described operations may be performed in variousother ways, for example, in an order different from the one describedabove.

Each of the functions of the described embodiments may be implemented byone or more processing circuits or circuitry. Processing circuitryincludes a programmed processor, as a processor includes circuitry. Aprocessing circuit also includes devices such as an application-specificintegrated circuit (ASIC), digital signal processor (DSP),field-programmable gate array (FPGA), and conventional circuitcomponents arranged to perform the recited functions.

What is claimed is:
 1. A reading device comprising: a carriage movablein a sub-scanning direction; an optical sensor mounted on the carriage,the optical sensor being configured to scan an object placed on acontact glass; a reference scale used as a reference when a dimension ofthe object is computed based on an image obtained as the optical sensorscans the object; a flat gauge to be scanned by the optical sensor tocalculate a corrective value used to correct the image obtained by theoptical sensor; and circuitry configured to calculate the correctivevalue based on a scanned image including the reference scale and theflat gauge obtained by the optical sensor, and correct, based on thecorrective value, a measurement image including an image of the objectand an image of the reference scale obtained by the optical sensor andcompute the dimension of the object based on the corrected measurementimage, wherein the reference scale extends in a main scanning directionorthogonal to the sub-scanning direction outside a range of imageacquisition in which the optical sensor scans the object to obtain theimage of the object as the carriage moves and inside a maximum movementrange in which the carriage is movable and the optical sensor obtainsthe image of the object, and wherein the flat gauge is arranged on thecontact glass inside the range of image acquisition, where a pluralityof first reference lines drawn on a face of the contact glass areoriented in the main scanning direction.
 2. The reading device accordingto claim 1, wherein the reference scale has a plurality of ticksextending in the sub-scanning direction, the plurality of ticks of thereference scale being drawn at positions separated from each other inthe main scanning direction.
 3. The reading device according to claim 2,wherein the reference scale extends in the sub-scanning direction andhas a plurality of ticks extending in the main scanning direction, theplurality of ticks of the reference scale being drawn at positionsseparated from each other in the sub-scanning direction.
 4. The readingdevice according to claim 3, wherein the flat gauge includes theplurality of first reference lines being parallel to each other and aplurality of second reference lines orthogonal to the plurality of firstreference lines, and the plurality of second reference lines areparallel to each other.
 5. The reading device according to claim 1,wherein the flat gauge is smaller than the range of image acquisition.6. The reading device according to claim 1, further comprising a memorythat stores a registered image including the reference scale and theflat gauge where the plurality of first reference lines are oriented inthe main scanning direction, wherein the circuitry is configured tocalculate the corrective value indicating an amount of movement for eachpixel of the scanned image to make the scanned image obtained by theoptical sensor close to the registered image stored in the memory. 7.The reading device according to claim 6, wherein the circuitry isconfigured to update the corrective value in response to a length oftime elapsed since the reading device started operating exceeding apredetermined operating time.
 8. An image forming apparatus comprising:the reading device according to claim 1; and an image forming deviceconfigured to form an image obtained by the reading device on asheet-like recording medium.